As portable devices, such as mobile communication systems, smart phones, tablet computers, laptops and navigation devices, become more advanced and powerful, these portable devices increasingly provide locational guidance to users in real time. More recently, portable devices have introduced a concept known as geo-fencing. A geofence is a virtual perimeter around a real-world location. Portable devices that implement geo-fencing functionalities may alert the user when the portable device has entered or exited an established geofence.
A geofence's perimeter may be virtually established around a point of interest such as an address, a store, or a home. Programs that incorporate geo-fencing allow an administrator of a geofence to set up triggers so when a device enters (or exits) the boundaries of the geofence (defined by the administrator), a text message or email alert is sent. Many geo-fencing applications incorporate Google® Earth, allowing administrators to define boundaries on top of a satellite view of a specific geographical area. Other applications may define boundaries by longitude and latitude or through user-created and Web-based maps.